Brandy Dopkin gave her then-11/2-year-old daughter Jordana a snack — a small piece of multigrain bread topped with peanut butter — just before they headed to Jordana's music class. At the time, the child showed no indications of a food allergy.

But that changed during the class: Someone noticed that Jordana's skin was breaking out in hives. Dopkin decided to take her daughter home, but by the time they arrived, Jordana's eyes were swollen shut and welts had formed on her neck. That prompted a dash to the emergency room, cutting in front of cars, rolling down her window to implore other motorists to get out of the way.

"I ran right in the emergency room and I said, 'My daughter is having an allergic reaction! Someone help me!' " said Dopkin.

Jordana is now 4. She has peanut, tree nut and shellfish allergies but hasn't had another allergic reaction.

Dopkin and her husband, David, will be among the more than 400 people expected Sunday at the Food Allergy & Anaphylaxis Network's Walk for Food Allergy at Meadowbrook Park in Ellicott City. Veronica Brown, vice president of communications for FAAN, said the walk has raised $14 million nationwidesince its inception in 2004. Proceeds are used for awareness and research.

According to a national study conducted in May, food allergies affect 8 percent of children in the U.S. That's an 18 percent increase over a decade ago.

The Dopkins, who live in Mount Washington, are taking part in the walk for the second consecutive year. They connect with other families whose children have allergies as well as work to educate family, friends and school staff about prevention.

"Once it comes into your home, you're suddenly connected to this bigger picture," said Brandy Dopkin. "Unfortunately, if it doesn't affect your immediate world you really aren't that aware of it."

Dr. Ruchi S. Gupta, a pediatrician and researcher at Children's Memorial Hospital in Chicago, was lead author in a national food allergy study that was administered to nearly 40,000 children during 2009-2010. The study found that New Jersey, Delaware and Maryland each had a 9.5 percent food allergy prevalence — the highest in the nation, along with Georgia, Florida and Nevada.

The Dopkins said they knew little about food allergies before Jordana's reaction. Now they've taught Jordana to ask "Does this have nuts in it?" before eating something.

For them, keeping abreast of food allergy information is also vital because David Dopkin is general manager of Miss Shirley's Cafe, a local restaurant chain owned by his family.

He said that Miss Shirley's general managers are alerted any time a patron mentions a food allergy to a server. "Not a day goes by now over the past year where a guest doesn't inform a server of an allergy," said David Dopkin.

Amy Kowitz of Owings Mills said she had her son Cory tested for allergies when he was 1 year old after he suffered from stomach problems. They discovered that Cory, now 11, has peanut and soybean allergies that they've managed to keep under control without a serious episode.

Cory said one of his worst bouts came at a basketball camp this year, when he touched a table where someone had eaten a peanut butter Snickers.

"My eyes were itching, they became red, got irritated and it became puffy around them," said Cory.

Though the Kowitzes have taken part in the Walk for Food Allergy since its inception, a scheduling conflict will prevent them from doing so this year. Kowitz said she initially got involved with the event to show her son how prevalent food allergies are among kids his age.

"It's actually really fun," Cory said. "There is this table where they have peanut-free and dairy-free treats, which I really like but I can't find usually. And I like the walk because I'm walking with my friends."